Bills

Vendor bills (the AP side of invoices). Same shape, same auto-fill, line rates default to item.purchase_price instead of selling price.

Resource shape

{
  "bill_id":      "bl_xyz",
  "bill_number":  "BILL-2026-0017",
  "vendor_id":    "ct_vendor",
  "vendor_name":  "ACME Supplies",
  "date":         "2026-05-12T00:00:00",
  "due_date":     "2026-05-26T00:00:00",
  "reference_number": "Invoice #5523",
  "place_of_supply": "IN-MH",
  "currency_code": "INR",
  "exchange_rate": 1.0,

  "line_items":   [ /* same shape as invoice line_items */ ],

  "sub_total":    700,
  "tax_total":    126,
  "total":        826,
  "payment_made": 0,
  "balance":      826,

  "status":       "DRAFT",   // DRAFT | OPEN | PARTIALLY_PAID | PAID | OVERDUE
  "notes":        null,
  "created_time": "...",
  "last_modified_time": "..."
}

Same query params as GET /invoices but with vendor_id instead of customer_id.

Required: vendor_id, date, place_of_supply, at least one line_items[]. Pass auto_approve: true to post the journal in the same call (status → OPEN).

POST /bills
Authorization: Bearer aibk_pat_…
Content-Type: application/json

{
  "vendor_id": "ct_vendor",
  "date": "2026-05-12T00:00:00",
  "place_of_supply": "IN-MH",
  "line_items": [{ "item_id": "it_widget", "quantity": 10 }],
  "reference_number": "Invoice #5523",
  "auto_approve": true
}

Anti-duplicate guard

Creates with the same (vendor_id, date, total) as an existing posted bill are refused with code: validation.invalid_value. Use Idempotency-Key for retry-safety; pass a distinct reference_number to legitimately register multiple bills with the same vendor on the same day.